Automatic washing machine having a variable speed drive



y 7, 1963 E. SCHMETTOW 3,088,303

AUTOMATIC WASHING MACHINE HAVING A VARIABLE SPEED DRIVE Filed Sept. 19,1961 4 Sheets-Sheet 1 I I; i 2 3/7 I Fig.2

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AUTOMATIC WASHING MACHINE HAVING A VARIABLE SPEED DRIVE Filed Sept. 19.1961 4 Sheets-Sheet 2 y 1963 E. SCHMETTOW 3,088,303

AUTOMATIC WASHING MACHINE HAVING A VARIABLE SPEED DRIVE 4 Sheets-Sheet 3Filed Sept. 19, 1961 May 7, 1963 E. SCHMETTOW 3,088,303

AUTOMATIC WASHING MACHINE HAVING A VARIABLE SPEED DRIVE Filed Sept. 19,1961 4 Sheets-Sheet 4 Unite States Patent 3,088,303 AUTUMATIC WASHINGMACHINE HAVING A VARIABLE SPEED DRIVE Erich Schmettow,Hohenbrunn-Riemeriing, Germany, as-

signor to Siemens-Electrogerate Aktiengesellschart, Berlin, Germany, acorporation of Germany Filed Sept. 19, 1961, Ser. No. 139,584 Claimspriority, application Germany Sept. 23, 1960 6 Claims. (Cl. 68-12) Myinvention relates to drum-type washing machines, particularly toautomatic electric washers, in which a laundry-receiving drum is drivenfrom an electric motor for slow rotation of the drum during washing andrinsing and fast rotation during subsequent spin-drying.

Such difierent rotating speeds of the drum can be obtained andexclusively controlled with the aid of -multi stage mechanicalspeed-change transmissions, but such transmissions occupy much space andrepresent an expensive component it three or more transmission rat1osare required. The expenditure in material and space increasesconsiderably with the ratio of the required maximum (spinning) andminimum (washing) speeds. For good spin-drying, however, the spinningspeed must be kept as high as feasible, Whereas the washing speed forbest laundering must have a much lower value, usually at about 50 rpm.Since furthermore the electric motors preferably employed for washingmachines are of the squirrel-cage type, because they are not susceptibleto trouble by sparking and require virtually no maintenance, and sincesuch motors have a poor starting characteristic, namely a low torque atlow speed and hence very low starting power, the design of a drive fordrum-type washers employing such motors involves considerabledifficulties which, as a rule, can be overcome only with heavy, largeand expensive motors and/or with the aid of large and complicatedtransmission mechanisms. Another possibility of adjusting differentdriving speeds resides in the use of a pole-switchable squirrelcagemotor. However, in order to obtain the abovementioned extreme change intransmission ratio between washing and spinning speeds, the necessarymotors would have to have a very high pole-number ratio, for example2:24 or more. Such motors are excessively heavy and expensive.

It is therefore an object of my invention, relating to automaticdrum-type washing machines of the type described above, to devise adrive which permits using a relatively small electric motor in bothstages of operation, namely for slow washing operation as well as forfast spindrying, while securing an economical performance and obtaininga transition from washing to spinning with a highest feasible torque ofthe drive m otor.

Another object of my invention is to devise a drive for such washingmachines which, in the event the operating voltage should fail duringthe spinning operation, will automatically and without appreciableauxiliary devices, return into an operating condition in which the drivecan readily commence with a new operating process. That is, the washingmachine when operating in dryspinning operation and then encounteringvoltage failure is supposed to return with particularly simple means andin a reliable manner into an operating condition which, as to drumspeed, either corresponds to the wash ing stage or approaches itsufficiently to permit restarting the motor with a sufdcient startingtorque until the speed is automatically increased again up to thespinning value.

To achieve these objects and in accordance with a feature of myinvention, I provide the drum-type washing machine between the electricdrive motor and the laundry-receiving drum with a variable-speedtransmis- 3,988,393 Patented May 7, 1963 sion mechanism whosetransmission ratio is continuously controllable from a lower to an upperlimit value, in combination with a speed-responsive regulating meanswhich preferably under direct or indirect control by the programming orother control device of the washing machine, automatically increase thedrum speed up to the desired high spinning speed. The transmission mechanism thus automatically controlled then operate constrainedly to alwaysmaintain the drive motor at a favorable point of its torquecharacteristic while the speed of the drum is being built up to thespin-drying value.

Such a washing-machine drive can readily be so designed that it willautomatically return to washing speed in the event the drive motor issubjected to voltage failure.

According to a more specific feature of my invention, theabove-mentioned control and resetting operations are obtained byproviding the ratio-regulating means of the transmission with acentrifugal device, such as a weight movable in dependence uponcentrifugal force, for continuously varying the drum-speed. Such acentrifugally regulated transmission is automatically effective toincrease the drum speed up to the desired maximum value at the beginningof a spin-drying operation and also sets the transmission mechanism backto low speed in the event of voltage failure.

According to a particularly simple embodiment of the invention, theelectric drive motor of the washing machine always operates at a fixedspeed and the speed change of the drum is effected exclusively by thechange in transmission ratio within the transmission mechanismconnecting the motor with the drum.

However, according to another, preferred feature of my invention, aconsiderable further improvement is achieved by providing for the inputmember of the regulatable transmission mechanism two selective speedsteps, a lower speed to be effective during washing operation and ahigher speed to be effective for spin-drying operation, the transmissionmechanism having a fixed transmission ratio at the lower speed of itsinput member and commencing its ratio-changing operation only when thespeed of the input member is switched to the higher value. Thiscombination of the variable-ratio transmission with a twostep primarydrive affords covering a particularly great range of speeds withrelatively simple means.

According to a more specific feature of the type just mentioned, thechange between the two steps of input speed for the variable-ratiotransmission is effected by means of a two-stage speed-change gearingbetween a single-speed electric motor and the input member of thetransmission mechanism. In such a machine, it is preferable to controlthe two-stage gear transmission by a control pulse supplied from theprogramming or control device of the washing machine, namely so thatwhen this device switches the machine from washing to spinning, the geartransmission is simultaneously switched from low gear to high gear, theregulator of the continuously variable transmission mechanism being soset that it responds to the switching to increased primary drivingspeed, thus commencing the above-described automatic increase of thedrum speed up to the desired spinning speed.

According to another, alternative feature of my invention, the change ininput speed applied to the input member of the variable-ratiotransmission mechanism is effected by providing the machine with apole-switchable induction motor which in this case may have a relativelysimple design because its pole number ratio need only be moderate, forexample 2:4, as the further increase in drum speed is effected by thevariable transmission between motor and drum.

According to a further feature of my invention, the

above-mentioned variable-ratio transmission comprises an endless V-beltwith belt sheaves of adjustable effective diameter, belt transmission ofthis type being generally known as such. The diameter-changing controlof one or both belt sheaves can then be effected directly by thecentrifugal regulator cooperating with a counter spring. When providingtwo adjustable belt sheaves, it is preferable to mount the spring, tooppose the centrifugal force, upon the displaceable portion of one ofthe sheaves and to mount the centrifugal weights upon the displaceableportion of the other sheave. In this manner, the spring and thepro-tension produced thereby have the effect of determining the rotatingspeed at which the centrifugal regulator will commence operating, andthe same spring then simultaneously serves to maintain substantiallyuniform tension in the belt.

Such a V-belt transmission in a washing machine according to theinvention may also be of the two-stage type. In this case, anintermediate shaft is provided between the motor shaft and the drumshaft. The intermediate shaft is preferably provided vvith twobelt-sheave portions which are fixed in the axial direction relative toeach other, and also with two belt-sheave portions which aredisplaceable axially in the same sense so that the displacementincreases the effective sheave diameter for one of the two belts andsimultaneously reduces the eifective sheave diameter for the other belt.In a transmission of this type, the axial pressure upon the V-belts inthe two transmission stages would be approximately equal, disregardingthe differences in the groove angle which in any event remain withinvery narrow limits. However, since the torques in such a plural-stagetransmission and hence the pulling forces transmitted by the respectivebelts, differ greatly from each other in accordance with the step-downor step-up ratio, the faster running belt would be subjected to aconsiderably higher pressure force than the other belt because the forceof the counter spring must adapt itself to the slowly running stagewhere higher torques are effective. In the fastrunning stage, the highpressure in conjunction with the high belt speed may result in excessiveheating and great wear of the belt.

According to a more specific feature of my invention, however, thesedifficulties are obviated as follows. A compensating spring is mountedon the intermediate shaft between an axially fixed belt portion and theaxially movable belt portions, and the force of the compensating springis directed against the action of the counter spring mounted on the drumshaft, thus reducing the axial stress imposed upon the belt in the fastrunning transmission stage. With the counter spring on the drum shaftand the compensating spring on the intermediate shaft thus acting inopposition to each other, the centrifugal regulating device correlatedto the motor shaft need overcome only the difference of the two springforces. This is favorable to the performance of the transmissionmechanism because this difference is relatively small if the centrifugalweights, when in starting position, are located in the vicinity of themotor-shaft axis where the centrifugal force is initially slight becauseof the small radius. During the regulating operation the radiusincreases, the centrifugal force also increases, and the differencebetween the two spring forces to be overcome by the centrifugal forcealso increases. Consequently, an adaptation of centrifugal force andspring forces is readily possible.

The above-mentioned and other objects, advantages and features of myinvention, said features being set forth with particularity in theclaims annexed hereto, will be apparent from, and will be described in,the following with reference to the embodiments of drum-type washingmachines according to my invention illustrated by way of example on theaccompanying drawings in which:

FIG. 1 shows schematically the components of a drumtype washing machineessential to the invention including the laundry-receiving drum, thevariable-ratio trans- 5- mission, a pole-switchable, drive motor and aprogramcontrol device.

FIG. 2 shows schematically in a substantially similar manner a washingmachine with a single-speed motor and a two-stage speed-change gearinterposed between the motor and the variable-ratio transmission.

FIG. 3 shows schematically a side view of part of FIG. 1 or 2.

FIG. 4 shows a side view similar to FIG. 3 but relating to a somewhatmodified design.

FIGS. 5a and 5b illustrate in section the upper and lower belt sheavesrespectively of the variable-ratio transmission according to FIGS. 1 to4, each illustration showing two different operating positions.

FIG. 6 is a speed-time diagram explanatory of the performance ofmachines according to the invention.

FIG. 7 shows in section a two-stage belt transmission of variable ratioapplicable in washing machines otherwise corresponding to those of thepreceding embodiments; and

FIG. 8 is an explanatory diagramrelating to the performance of thetransmission according to FIG. 7.

As shown in FIG. 1, the drum 1 of a washing machine is driven from apole-switchable squirrel-cage motor capable of selectively operating attwo speeds depending upon which group of poles is energized at a time.Such motors are commercially available as standard products. They mayhave two and four poles, for example, to operate at a speed ratio of2: 1. Driving power is transmitted from the shaft 11 of the motor 2 tothe shaft 19 of the drum by a variable-ratio mechanism consisting of aV-belt drive which comprises a two-part belt sheave 3 on the drum shaft19, a two-part belt sheave 4 on the motor shaft 1 1, and an endlessV-belt 8. The motor 2 is energized from power-supply terminals 20 undercontrol by a programming control device 7 illustrated as a drum-typecontactor in planar developed form, which is provided with contactsegments 5 and fixed contacts 6. The control device 7 is essentially anelectrically driven timer as customary for automatic washing machines.When the control device 7 is in Low position, one group of poles inmotor 2 is active for operation of low speed and the drum 1 is drivenfor washing operation. When the device 7 advances to High posi-' tion,the other group of poles in motor 2 is energized for driving the drum 1at higher speed. As explained, the transmission 3, 4, 8 now becomeseffective to change its transmission ratio so as to gradually increasethe drum speed above the value that it would assume if the drum weresimply driven at the speed of motor 2. Such increase continues until thedrum 1 has reached the desired high spin-drying speed. Details of thevariable-ratio transmission and its operation will be described in alater place.

The embodiment schematically illustrated in FIG. 2 is to some extentsimilar to that of FIG. 1, identical components being denoted by thesame reference numerals respectively. According to FIG. 2, asingle-speed two-pole drive motor 22 is used. It drives a two-stagedmechanical gear transmission 24 which in turn drives the input sheave 4of the above-mentioned variableratio transmission. The two speed stepsof gear transmission 24 are electromagnetically controlled by respectivecontrol windings 26 and 28 so that only the one gear step is activewhose appertaining control winding is energized at a time. The programcontrol device 27, when turning from Stop to Low position, energizes'bymeans of its contact segments 25, the motor 22 and simultaneously thecontrol winding 26 so that the drum 1 is driven for washing operation atslow speed. When thereafter the control device 27 switches .to Highposition, the motor 22 remains energized but now the control winding 28is energized so that the input sheave 4 of the variable-ratiotransmission operates at higher speed and the variable-ratiotransmission commences to increase the drum speed up to the spinningvalue.

As will be more fully apparent from FIGS. 5a and 5b, each belt sheave 3and 4 in FIGS. 1 and 2 comprises a half-portion fixed to the shaft onwhich the sheave is mounted, whereas the other half portion is axiallydisplaceable so that the V-groove of the sheave can become wider ornarrower. This should be kept in mind with reference to the lateral viewillustrated in FIG. 3, showing the two extreme positions of the endlessbelt 8. Shown by a full line is the operating condition of the belt forthe low drum speed. Shown by a broken line is the operating conditionfor the high drum speed.

FIG. 4 illustrates a modified embodiment in which the belt sheave 3 onthe shaft 19 or drum 1 has a fixed effective diameter (i.e. does notconsist of two portions of which one is axially displaceable relative tothe other) and only the belt sheave 4 on the motor shaft 11 can vary itseffective diameter for changing the transmission ratio. In this case, atensioning roller 9 is provided for compensating the different beltlengths during changes in transmission ratio. The roller 9 is pressedagainst the belt 3 in the direction of the arrow, for example by meansof a spring, and may be journalled, for example, on an arm (not shown)pivotally mounted on the motor shaft 11. During operation at low drumspeed, the tensioning roller 9 is in the full-line position at the left,and the V-belt 8 ms with the smallest diameter of the driving sheave 4on the motor shaft 11. At the highest drum speed, the roller 9 occupiesthe broken-line position, and the driving sheave 4 is active with itslargest diameter.

As more fully shown in FIGS. 5a and 5b, the driving belt sheave 4 in amachine according to FIGS. 1 or 2 comprises a disc 12 rigidly joinedwith the shaft 11 of the electric motor 2, and a disc 13 axiallydisplaceable on the shaft 11. A helical pressure spring 14 tends toforce the disc 13 away from disc 12 to the limit position shown in theupper portion of FIG. 5b. In this position, the driving belt is in itsinnermost operating position 8a so that a relatively smalldriving-sheave diameter is effective. This position corresponds to thewashing operation of the drum. When passing to the spin-dryingoperation, initiated by switching of the motor 2 (FIG. 1) to high speed,the revolving speed of the motor shaft 11 increases. When it reaches agiven value, a centrifugal weight 15, pivotally connected at 16 with thedriving disc 12 by a sleeve 17, is lifted and then forces a pressure dog18 against the displaceable disc 13. As a result, the disc 13 isgradually forced toward the disc 12 in opposition to the force of spring14 to the limit position shown in the lower portion of FIG. 5b. In thelatter position, the driving belt is in the position 8b in which thelargest diameter of the driving sheave is effective.

The driven sheave 3 (FIG. 5a) comprises a disc 20 rigidly joined withthe shaft 19 of the washer drum 1, and a disc 21 am'ally displaceablerelative to disc 20. A helical compression spring 22 forces the disc 21toward the disc 20, so that the disc 21 assumes the brokenline positionduring washing operation and the driving belt occupies the position 8acorresponding to the largest effective diameter of the driven sheave 3.During spinning-drying operation, the belt is forced downward to theposition 8b so that the disc 21 occupies the fullline position in whicha smaller diameter of the driven sheave 3 is effective. This is due tothe action of the centrifugal Weight 15. If desired, however, the uppersheave 3 may also be provided with a centrifugal device corresponding tothat shown in FIG. Sb and set to operate simultaneously with, and in thesame manner as, the device described above with reference to FIG. 5b.

The coordinate diagram of FIG. 6 is typical of the performance obtainedwith a washing machine according to the invention. The abscissa denotestime (t), and the ordinate indicates the rotating speed (n) of the drumin revolutions per minute. Upon to the moment t the machine runs inwashing operation. At this moment, the two-stage drive is switched fromLow to High by the program control device of the machine (7 in FIG. 1,27 in FIG. 2). Now the drum speed n increases up to the moment t inwhich the centrigual regulator (15) becomes act-ive. The moment t isreached when balance obtains between the centrifugal force of theregulator and the force of the counter spring. These two forces must begiven such an approximate dimensioning that 1 would be attained at abouta drum speed of 60 to 70% of the speed effective if only the highswitching stage of the gear transmission 24 (FIG. 2) or of thepole-switchable motor 2 (FIG. 1) were permitted to operate and thevariable-ratio transmission were kept at a fixed ratio. At thejust-mentioned speed the maximum power of the motor is substantiallyreached. Beginning with the moment t the regulator 15 causes the speedof drum 1 to be increased by the continuously regulatable transmis sionup to the maximum value which is reached at the moment t That is, frommoment 1 to moment t the drum speed is being increased from the lowwashing speed up to the spinning speed, and the spin-drying operationproper commences with the moment I A two-stage variable-ratiotransmission embodying the above-mentioned features of the inventionwill be described presently with reference to FIG. 7 and with referenceto the diagram of FIG. 8 indicating the forces acting upon the counterspring and compensating spring in dependence upon the amountdisplacement.

The transmission mechanism "shown in FIG. 7 is applicable in lieu of thesingle-stage variable-ratio transmission of the embodiments describedabove, in conjunction with an electric drive motor and a control deviceas shown in FIG. 1, or in conjunction with a motor, twostep geartransmission and control device as shown in FIG. 2. It may be assumed,for example, that the input sheave of the variable-ratio mechanismaccording to FIG. 7 is driven from a pole-switchable motor with two andfour selectively operable poles. Denoted by 31 in FIG. 7 is the shaft ofthe washer drum, by 32 the shaft of the motor, and by 33 theabove-mentioned intermediate shaft.

The driving sheave on the motor shaft 32 comprises an axially fixedportion 34 and an axially displaceable portion 35 which jointlycooperate with a Vbelt 36. Mounted on the motor shaft and axially rigidrelative thereto is a guiding body 37 for centrifugal Weights 38. Whenthe motor shaft rotates at a speed above a given value, the weights 38move outwardly in the directions indicated by arrows 39 and press theaxially displaceable portion of the belt sheave toward the left in thedirection of the arrow 40 thus providing for the increased driving speedof the drum required for spin-drying operation.

The intermediate shaft 33 carries two axially fixed beltsheave discs 41and 42 between which an am'ally displaceable middle structure is mountedwhich forms two sheave portions 43 and 44. The belt sheave 36 engagesthe sheave portions 42 and 44. Another belt 45 engages the sheaveportions 41 and 43 and serves for driving the belt sheave on the drumshaft 31.

The drum shaft 31 carries an axially fixed sheave disc 46 and an axiallydisplaceable disc 47, both cooperating with the V-belt 45. A helicalcounter spring 48 mounted on the drum shaft 31 tends to force thedisplaceable disc 47 toward the fixed disc 46. A helical compensatingspring 49 is mounted on the intermediate shaft 33 between the axiallyfixed portion 42 and the axially displaceable middle structure 43, 44.Spring 49 acts in opposition to the force of the counter spring 48.

In FIG. 7, the belt position corresponding to the wash ing operation isshown by full lines, whereas the belt position corresponding to thespin-drying operation is indicated by broken lines.

In the graph shown in FIG. 8, the horizontal reference line indicatesthe direction of displacement caused by the centrifugal motion of theWeights 38, this motion being in the direction of the arrow 40 andcausing a compression of the counter spring 48 and of the compensatingspring 49. The amount of displacement thus centrifugally effectedextends from a to Plotted on the displacement line are the spring forcesof the counter spring 48 (G G and the spring forces of the compensatingspring 49 (A A so that the force difference F or F to be overcome 'bythe centrifugal force of the weights 38 is apparent. The increase of thedifference valve from F to F can be dimensioned by corresponding choiceof the springs 48 and 49 so that it corresponds to the increase incentrifugal force acting upon the weight 38 during automatic regulatingoperation.

When employing such a two-stage belt mechanism, the increase in force ofthe counter spring on the drum axis can be kept very small, in somecases even negative, corresponding to the torques to be transmitted onthe drum shaft. With the corresponding increase in force of thecompensating spring on the intermediate shaft, the increase in thedifierence between the two spring forces can be so dimensioned that itcorresponds to the increase of the centrifugal force acting upon thecentrifugal regulator so that a favorable regulating characteristic isobtained.

Upon study of this disclosure, it will be obvious to those skilled inthe art that my invention is amendable to a variety of modifications andhence can be given embodiments other than particularly illustrated anddescribed herein, without departing from the essential features of theinvention and within the scope of the claims annexed hereto.

1 claim:

In a drum-type washing machine having a laundryreceiving rotatable drum,drive means for said drum, and a program control device connected withsaid drive means for sequentially switching it to operate at a lowerspeed range for Washing operation and at higher speed range forcentrifuging operation, said drive means including a motor and atwo-step gear transmission mechanism dis posed between said motor andsaid drum and shiftable between a first and second speed fortransmitting power to said drum and increasing the speed thereof, acontinuously variable V-belt transmissionv having a pair of sheaves eachhaving a displaceable disc and connected between said two-steptransmission mechanism and said drum for controlling acceleration ofsaid drum within said higher speed range, and a centrifugal weightdevice joined with a first one of said sheaves and engaging thedisplaceable disc of said first sheave for displacing the latter independence upon the second speed of said two step transmission, saidcontrol device having means =for sending a signal pulse to shift saidtransmission from a said first speed to said second speed, saidcentrifugal device being responsive to the two-step transmissionreaching said second speed.

2. In a washing machine according to claim 1, said motor having a singleoperating speed.

3. In a washing machine according to claim 1, said V-belt transmissionhaving a variable transmission ratio, said first sheave being ofvariable effective diameter and coaxial-1y joined with said drive means;a counter spring engaging said first sheave and biasing it in thedirection required to reduce said transmission ratio, said centrifugalweight device being movable outwardly by centrifugal force andoperatively connected with said first sheave for varying said diameterin opposition to said spring to increase said transmission ratio.

4. A washing machine according to claim 1, including a counter spring inengagement with said displaceable disc of said first one of said sheavesfor biasing it away from said fixed disc of said one sheave, and saidweight means having a pivot axis in fixed relation to said axially fixeddisc of said one sheave and being centrifugally movable outwardly aboutsaid axis for displacing said displaceable disc of said one sheave inopposition to force transmitted by said belt from said spring.

5. In a drum-type washing machine having a laundryreceiving rotatabledrum, drive means for said drum, and a control device connected withsaid drive means for sequentially switching it to operate at low speedfor washing operation and high speed for spin-drying operation, thecombination of a transmission mechanism disposed between said drivemeans and said drum and having a transmission ratio continuouslyvariable between a lower and an upper limit, said mechanism havingcontrol means responsive to operation of said control device for causingsaid ratio to continuously vary in the drum-speed increasing sense up tothe spin-dry speed when said drive means is switched from washing tospin-drying operation, said transmission mechanism comprising atwo-stage V- belt transmission having a first sheave coaxially joinedwith said drive means, a second sheave coaxially joined with said drum,an intermediate shaft parallel to the axis of said two sheaves, a twinsheave on said shaft, and two endless belts drivingly connecting saidfirst sheave with said twin sheave and connecting said twin sheave withsaid second sheave respectively; each of said first and second sheaveshaving two component discs of which one is axially fixed and the otheris axially displaceable, said two discs forming together a belt-engaginggroove whose effective diameter varies with the displacement of saidother disc; a centrifugal weight device joined with said first sheaveand engaging the displaceable disc of said first sheave for displaceingit in dependence upon the speed of said drive means; a counter springengaging said displaceable disc of said second sheave and having a forcedirection opposed to the action of said centrifugal weight device; saidtwin sheave comprising two axially fixed discs and two intermediate discmembers jointly displaceable axially in the same sense so as to formtogether with said two latter fixed discs two belt-engaged grooves whichinversely vary their respective diameters with axial displacement ofsaid disc members; and a compensating spring mounted on saidintermediate shaft and in biasing engagement with said disc member in aforce direction opposed to the effect of said counter spring, wherebysaid compensating spring reduces the axial stress imposed upon the beltrunning at greater speed than the other.

6. In a washing machine according to claim 5, said counter spring andsaid compensating spring having respective spring characteristicsadapted to each other so that the difference of their respective forcesincreases substantially in accordance with the increase in centrifugalforce of said centrifugal device during the ratio-changing operation ofthe transmission mechanism.

References Cited in the file of this patent UNITED STATES PATENTS2,253,634 Mack Aug. 26, 1941 2,311,924 Bassett Feb. 23, 1943 2,496,061Miner Ian. 31, 1950 2,651,210 Clark Sept. 8, 1953 2,881,633 Warhus Apr.14, 1959 2,942,447 Rickel et al. June 28, 960

FOREIGN PATENTS 143,605 Australia Sept. 27, 1951

1. IN A DRUM-TYPE WASHING MACHINE HAVING A LAUNDRYRECEIVING ROTATABLEDRUM, DRIVE MEANS FOR SAID DRUM, AND A PROGRAM CONTROL DEVICE CONNECTEDITH SAID DRIVE MEANS FOR SEQUENTIALLY SWITCHING IT TO OPERATE AT A LOWERSPEED RANGE FOR WASHING OPERATION AND AT HIGHER SPEED RANGE FORCENTRIFUGING OPERATION, SAID DRIVE MEANS INCLUDING A MOTOR AND ATWO-STEP GEAR TRANSMISSION MECHANISM DISPOSED BETWEEN SAID MOTOR ANDSAID DRUM AND SHIFTABLE BETWEEN A FIRST AND SECOND SPEED FORTRANSMITTING POWER TO SAID DRUM AND INCREASING THE SPEED THEREOF, ACONTINUOUSLY VARIABLE V-BELT TRANSMISSION HAVING A PAIR OF SHEAVES EACHHAVING A DISPLACEABLE DISC AND CONNECTED BETWEEN SAID TWO-STEPTRANSMISSION MECHANISM AND SAID DRUM FOR CONTROLLING ACCELERATION OFSAID DRUM WITHIN SAID HIGHER SPEED RANGE, AND A CENTRIFUGAL WEIGHTDEVICE JOINED WITH A FIRST ONE OF SAID SHEAVES AND ENGAGING THEDISPLACEABLE DISC OF SAID FIRST SHEAVE FOR DISPLACING THE LATTER INDEPENDENCE UPON THE SECOND SPEED OF SAID TWO STEP TRANSMISSION, SAIDCONTROL DEVICE HAVING MEANS FOR SENDING A SIGNAL PULSE TO SHIFT SAIDTRANSMISSION FROM A SAID FIRST SPEED TO SAID SECOND SPEED, SAIDCENTRIFUGAL DEVICE BEING RESPONSIVE TO THE TWO-STEP TRANSMISSIONREACHING SAID SECOND SPEED.